Police responded to the intersection of Almond and East Elkhart Streets around 3 a.m. on Wednesday.
Police say the two men were walking a dog when they were shot by an unidentified man.
Police found a 35-year-old man who was shot in the arm, and a 27-year-old man shot in the neck, chest and abdomen.
The 27-year-old man is said to be in critical condition and undergoing surgery.
The gunman was last seen wearing grey zip-up jacket, long pants, and black shoes, fleeing eastbound on Elkhart Street, according to police.
Police said the motive for the shooting is believed to be an argument.
Investigators say officers were able to watch surveillance video of parts of the incident but need more angles and details to finish sorting it out.
They say they believe the shooter lives in that area.
Philadelphia police are also investigating another shooting about an hour earlier that left two teens and an innocent bystander injured after at least 21 shots were fired in the city's Tioga section.
Police say in the Tioga shooting, teenagers were out walking around at 19th and West Allegheny around 2 a.m. on Wednesday.
Witnesses say two groups got into an argument and that someone started shooting.
Two teens, a 15-year-old and a 17-year-old, were both shot in the leg. A 44-year-old innocent bystander was also shot in the lower back.
"It appears that the shooter was firing the shot into the crowd of juveniles," said Chief Inspector Scott Small with the Philadelphia Police Department. "All three of our victims are very, very lucky. They're all shot one time and we know at least 21 shots were fired because we found 21 spent shell casings."
Anyone with information about either shooting is urged to contact the Philadelphia Police Department's tipline at 215-686-TIPS.
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